Would it work with your design to put the buttons on top of the MSO rather than nested in the MSO? That seems easier. Some designers also leave a bar at the top or bottom of the page to let readers swipe between articles.

Why don't your buttons work? They should. If your buttons are jumping to the next or previous page, don't use the Go to Next/Previous Page action. Instead, use the navto:// format to jump to the next/previous article.